CN106537108B

CN106537108B - Flexible leakage test cavity capable of being evacuated

Info

Publication number: CN106537108B
Application number: CN201580014633.0A
Authority: CN
Inventors: 亨德里克·范·特里斯特; 西尔维奥·德克尔
Original assignee: 英福康有限责任公司
Priority date: 2014-03-18
Filing date: 2015-03-12
Publication date: 2020-05-08
Anticipated expiration: 2035-03-12
Also published as: AU2019201019B2; DE102014205027A1; CN106537108A; CN110044558A; EP3435054B1; AU2015233645A1; AU2015233645B2; JP2020064073A; US20170097275A1; EP3120128B1; JP6640103B2; JP6880161B2; US10119883B2; EP3435054A1; WO2015140042A1; AU2019201019A1; CN110044558B; EP3120128A1; JP2017508164A

Abstract

The invention relates to a flexible test chamber (10) for leak testing of a sample, which can be evacuated and has a chamber wall (12) surrounding a test chamber volume (36). The flexible test chamber (10) is characterized in that at least one area of the chamber wall consists of two membrane layers (18, 20) of chamber wall material, wherein at least the membrane layer (20) facing the test chamber volume (36) is made of a flexible material; and in that between the two film layers (18, 20) an overpressure relative to the atmosphere surrounding the test chamber (10) is adapted to be generated.

Description

Flexible leakage test cavity capable of being evacuated

Technical Field

The present invention relates to an evacuable test chamber for leak testing of a test specimen.

Background

One type of test chamber is a membrane chamber, which for example comprises chamber walls made of a flexible membrane. Such a test chamber is described in european patent EP0741288a 1. The test specimen may be a food packaging bag, for example, which will be tested for air tightness. The test specimen is placed into the open test chamber. The test chamber is then closed and evacuated, with the flexible chamber walls (membrane chamber walls) against the sample. The term "vacuum" is not to be understood here as an absolute vacuum, but generally as a pressure lower than the atmospheric pressure surrounding the test chamber. The walls of the flexible test chamber abut the test sample once the pressure in the test chamber is lower than the pressure of the atmosphere surrounding the test chamber. Thus, the term "vacuum" should also be understood as creating a negative pressure, not necessarily an absolute vacuum.

When the flexible test chamber is closed, problems arise in that: due to the elasticity or flexibility of the flexible chamber wall material, a certain amount of gas will be enclosed in the test chamber. The faster the chamber is closed, the larger the volume of gas enclosed, since the flexible chamber wall material expands due to the resistance of the gas and there is no additional gas volume added during the closing process. So that the duration of the evacuation process of the test chamber is increased. When the cavity is rapidly closed, the increase in velocity causes a corresponding decrease in velocity during the time it is evacuated, since the trapped volume of gas must also be evacuated.

Disclosure of Invention

It is an object of the present invention to provide an improved test chamber and to create an improved method for leak testing.

An evacuable flexible test chamber for leak testing of a sample, the test chamber having a chamber wall surrounding a test chamber volume; the method is characterized in that: at least one part of the cavity wall is composed of two film layers of cavity wall material, wherein at least the film layer facing the test cavity volume is made of a flexible material and between the two film layers an overpressure relative to the atmosphere surrounding the test cavity is adapted to be generated, wherein the cavity wall surrounding the test cavity volume is composed of two cavity wall parts that fit on top of each other, wherein a first cavity wall part forms the bottom of the test cavity and a second cavity wall part forms the top of the test cavity, wherein the film layer facing away from the test cavity volume has a rigid structure; the two film layers are convexly raised; an overpressure in the range of 80 to 120 mbar is present in the two membrane layers compared to the atmosphere surrounding the test chamber.

A method for leak testing a sample located in the test chamber, comprising: an overpressure between the film layers is generated before the cavity is closed.

The chamber wall of the test chamber according to the invention, which surrounds the test chamber volume in the closed condition, consists of two film layers of the chamber wall material at least in one region. The two layers thus constitute the wall portion of the bilayer, i.e. the bilayer wall. At least the membrane layer facing the test chamber volume and containing the test sample therein is made of a flexible material, e.g. a film material. According to the invention, an overpressure can be formed or already taken up by the overpressure in the intermediate volume enclosed by the two membrane layers with respect to the atmosphere surrounding the test chamber. The overpressure is preferably in the range of about 100 mbar compared to the surrounding atmosphere. Thus, the overpressure may be in the range of about 80 to 120 mbar compared to the surrounding atmosphere. In the intermediate volume between the two cavity wall membrane layers, a gas, a liquid, a foam or a gel may be provided. Due to the presence of the overpressure, the film layer of flexible material bulging convexly towards the test specimen towards the test chamber volume with the chamber open.

When the test chamber is closed, the overpressure between the two membrane layers counteracts the resistance of air, so that the flexible membrane layer does not trap any additional gas volume. Due to the convex bulge towards the test specimen, the flexible membrane layer is pressed against the test specimen and deformed by the latter. In this way, the volume of the test chamber to be evacuated is reduced after the test chamber is closed.

It is particularly important that at least the membrane layer facing the test specimen and the test chamber volume is made of a flexible material. The second membrane layer facing away from the test chamber volume may be rigid or also made of a flexible material. The walls of the test chamber may be made completely or partly of a flexible material, such as a thin film material. It is conceivable that the walls of the test chamber are formed continuously as a single sheet and placed around the test specimen. Alternatively, the chamber wall may be comprised of a two-part chamber wall adapted to fit over each other. The boundary region of the chamber wall may be secured with a rigid frame. The cavity wall sections adapted to be placed on top of each other may be guided by hinges or may be connected to each other.

After the sample has been placed in the test chamber and before the test chamber is closed, an overpressure in the range of about 100 mbar should occupy or be generated in the intermediate volume between the two film layers. To this end, the intermediate volume may be connected to an air pump which generates the overpressure. Furthermore, it is also conceivable to use a pressure relief valve, for example, between the two film layers to prevent pressures above about 120 mbar.

Between the specimen and the test chamber body, a gas-conducting material, for example a gas-conducting mat made of a non-woven material, should be inserted for allowing a gas flow between the specimen and the chamber wall. The gas conducting material may extend along the entire inner side of the walls of the test chamber.

The flexible chamber wall may be clamped in a rigid frame. Preferably, two flexible chamber walls, which are each clamped in a circular ring-shaped frame, for example, are placed on top of each other. A gas seal should be provided between the two frames. A clamp may press the two frames against each other. In at least one region, a hinge may be provided between the two frames.

Preferably, a pressure sensor may be provided in the intermediate volume between the two membrane layers for measuring the pressure between the two membrane layers. The measured pressure helps to monitor whether the pressure in the intermediate volume is within a desired range of about 100 mbar.

Further, the gas tightness of the two membrane layers may be monitored by monitoring the pressure between the two membrane layers. If one of the two film layers is defective, the pressure between the two film layers is reduced.

Further, when the test chamber is closed, a check as to whether a sample is present in the test chamber may be performed by monitoring the pressure between the two membrane layers. When the chamber with double chamber walls is closed, the pressure between the two membranes will vary, because the convex bulge is pressed against the sample or the opposite chamber wall. If the sample is in the test chamber, the pressure will be greater than it would be if no sample were set. It is therefore possible to identify at an early stage the situation in which the sample is not actually placed.

Drawings

Hereinafter, exemplary embodiments of the present invention are described with reference to the accompanying drawings. Wherein:

fig. 1 shows a schematic cross-sectional view of the exemplary embodiment in an open state when the cavity is being closed;

fig. 2 shows a cross-sectional view of fig. 1 in a closed state of the cavity; and

fig. 3 shows a cross-sectional view of the exemplary embodiment in a closed state of the cavity before the cavity is evacuated.

Detailed Description

The test chamber 10 comprises a chamber wall 12 which is composed of two

chamber wall sections

14, 16. The chamber wall section 16 is the bottom of the test chamber 10 and the test chamber wall 14 is the lid of the test chamber 10. The cavity wall section 16 is rigid and made of metal, for example. As seen above, the

cavity wall sections

14, 16 have a circular shape and are fixed by

rigid frames

22, 24, which

rigid frames

22, 24 are formed in a ring shape at their boundary areas. Other shapes of the

cavity wall sections

14, 16 are also conceivable, in which other shapes the

cavity wall sections

14, 16 comprise at least one rectilinear side, as seen above. The upper loop 22 sealingly secures the two film layers 18, 20 together at their outer edge regions. Thus, an air-tightly enclosed intermediate volume 26 is defined between the two

membrane layers

18, 20. In the intermediate volume 26, a pressure of about 80-90 mbar prevails, which counteracts the air resistance that is experienced when the upper chamber wall section 14 is closed in the direction indicated by the arrow in fig. 1. Due to the overpressure, the two film layers 18, 20 bulge convexly to the outside. When the test chamber 10 is not closed, the lower membrane layer 20 bulges convexly towards the test specimen 28. The annular frame 22 is provided with sealing portions, not shown in the figures, for hermetically closing the intermediate volume 26.

A pressure sensor 30 is arranged in the intermediate volume 26 between the two

membrane layers

18, 20 and is connected to a pressure measuring instrument P for measuring the pressure of the intermediate volume 26. By monitoring the pressure in the intermediate volume 26, a leakage of the membrane layers 18, 20 or the frame 22, i.e. the upper chamber wall section 14, can be detected. The pressure may also indicate whether the test sample 28 is within the test chamber 10 and may indicate the volume of the test sample. In the closed state of the test chamber as shown in fig. 2, the pressure of the intermediate volume 26 increases the larger the volume of the test specimen 28 when measured by the pressure measuring instrument P.

By means of the pressure measuring instrument P, the pressure of the intermediate volume 26 can be adjusted precisely to the desired value when it is filled. Preferably, the upper chamber wall section 14 is provided with a valve connection, not shown in the figures, for connecting a gas pump or a compressed gas source by means of which the intermediate volume 26 can be filled. Alternatively, it is also conceivable that the intermediate volume 26 is filled with a liquid, foam or gel. A pressure relief valve of the upper chamber wall section 14, also not shown in the figure, may prevent excessive pressure from developing between the two

membrane layers

18, 20.

Between the specimen 28 and each of the two chamber wall sections 14, 16 a respective gas-conducting

fabric

32, 34, for example a non-woven or woven material, is inserted, which results in gas escaping from the test chamber volume 36 during evacuation of the test chamber 10 in the closed state of the test chamber 10 shown in fig. 2. The fabric is also referred to as a membrane in the following.

The two ring frames 22, 24 are connected to each other air-tightly by a first inner ring seal 38 and a second outer ring seal 40. In the closed state, the two ring frames 22, 24 are pressed against each other by a clamping device not shown in the figures.

After the test specimen 28 has been placed on the gas conducting membrane 34 residing on the lower chamber wall portion 16, the second gas conducting membrane 32 is placed over the test specimen, as shown in FIG. 1. In this way, the upper chamber wall section 14 is lowered in the direction of the arrow downwards towards the specimen 28 and the lower chamber wall section 16 in order to close the test chamber 10.

When the test chamber is being closed, the lid, i.e. the upper chamber wall section 14, can be moved faster than before, because the overpressure in the intermediate volume 26 counteracts the gas resistance experienced when the lid is lowered and prevents the flexible membrane layer from being distorted. Since the lower film layer 20 bulges convexly towards the test specimen 28, in the closed state of the test chamber 10, the test chamber volume between the two

chamber wall sections

14, 16 is already reduced before the test chamber 10 is evacuated. The remaining residual volume to be evacuated will therefore be smaller. The test chamber according to the invention thus allows the test chamber to be closed and evacuated more quickly and thus put into use more quickly.

Claims

1. An evacuable flexible test chamber for leak testing of a sample, the test chamber having a chamber wall surrounding a test chamber volume; the method is characterized in that: at least one part of the cavity wall is composed of two film layers of cavity wall material, wherein at least the film layer facing the test cavity volume is made of a flexible material and between the two film layers an overpressure relative to the atmosphere surrounding the test cavity is adapted to be generated, wherein the cavity wall surrounding the test cavity volume is composed of two cavity wall parts that fit on top of each other, wherein a first cavity wall part forms the bottom of the test cavity and a second cavity wall part forms the top of the test cavity, wherein the film layer facing away from the test cavity volume has a rigid structure;

the two film layers are convexly raised; an overpressure in the range of 80 to 120 mbar is present in the two membrane layers compared to the atmosphere surrounding the test chamber.

2. The evacuable, flexible test chamber of claim 1, wherein: a gas, liquid, foam or gel is contained between the two film layers.

3. The evacuable, flexible test chamber of claim 1, wherein: a pressure measuring instrument for measuring pressure is arranged between the two membrane layers.

4. The evacuable, flexible test chamber of claim 1, wherein: the chamber wall comprises a layer of gas conducting material on its side facing the test chamber volume.

5. A method for leak testing a test specimen located in the test chamber of claim 1, wherein: an overpressure between the film layers is generated before the cavity is closed.

6. The method of claim 5, wherein: the gas tightness of the chamber walls was checked by monitoring the pressure between the membrane layers.

7. The method of claim 5 or 6, wherein: the check as to whether the sample is within the test chamber is performed by monitoring the pressure between the two membrane layers while the test chamber is being closed.